Production of hydrocarbon fuels from plastics

ABSTRACT

Disclosed herein is a kiln  100  for use in the production of hydrocarbon fuels from plastics. The kiln  100  comprises a scrubber  200  in fluid communication with a reaction chamber  130 , the scrubber  200  being configured to condense hydrocarbons in the reaction chamber gas product stream  501  above a predetermined upper hydrocarbon range for returning to the reaction chamber  130  for further heating in the absence of oxygen. Also disclosed herein is a method of converting waste plastics to a commercially-useful form by way of diesel or the like. The method comprises treating a crude fuel produced from plastics in a pyrolytic process with a first extraction step comprising counterflow liquid-liquid extraction, and a second extraction step comprising counterflow extraction of solvents from the first extraction step.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of the following AustralianProvisional Patent Applications: AU2015904828, filed on 24 Nov. 2015 andentitled KILN FOR USE IN THE PRODUCTION OF HYDROCARBON FUELS FROMPLASTICS; AU2016901654, filed on 5 May 2016 and entitledPLASTICS-DERIVED FUELS AND METHODS OF MAKING SAME; and AU2016902869,filed on 21 Jul. 2016 and entitled PLASTICS-DERIVED FUELS AND METHODS OFMAKING SAME II, the disclosures of which are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to the production ofhydrocarbon fuels from waste plastics materials.

BACKGROUND

Plastics is a material typically formed of long chain organic polymers.As a result of the relatively low cost of production and ease ofmanufacture, plastics materials are used in a wide variety of productsaround the world, including a large number of disposable products suchas packaging. As consumption of disposable products formed of plasticsmaterials increases, the associated waste plastics material alsoincreases, leading to environmental concerns due to the long life of theplastics materials if sent to landfill. Other issues associated with thedumping of waste plastics include soil contamination and infertility.

Plastics recycling is the process of recovering scrap or waste plasticsand reprocessing the material into useful products. However, unlikemetal recycling, the recycling of plastics materials can be challengingdue to low economic returns. Recycling of plastics can face furtherdifficulties as a result of the chemical nature of the long chainorganic polymers which can make them difficult to process. Furthermore,waste plastics materials often need sorting into the various plasticresin types, e.g. polyethylene terephthalate (PET), high-densitypolyethylene (HDPE), polyvinyl chloride (PVC), for separate recyclingtreatments.

As plastics are formed of long chain organic polymers containinghydrogen and carbon, processes have been developed for the conversion ofthe long chain polymer into shorter length hydrocarbon fuel productssuch as petrol or diesel. These processes typically involve pyrolysis ofthe plastics material to reduce the long-chain polymers to polymers ofsmaller chain length.

Current techniques for processing plastics materials into hydrocarbonfuel products often result in the production of wax and tar typeproducts that can foul equipment and piping used in the process. Inaddition, the presence of particulate materials introduced to the systemor formed in the course of the reaction can result in the formation of alow purity, difficult to handle sludge-like products when condensed.Furthermore, hydrocarbons condensed directly after the pyrolysisreaction are generally required to be re-heated in order to thenseparate out the desired hydrocarbons.

An alternative to landfill disposal of plastics is incineration.However, this has posed problems such as damage to the furnace and theemission of harmful gases and an offensive odour. Society'sever-increasing environmental consciousness has deemed incineration alargely unpopular and unsustainable method of disposing of wasteplastics.

In the United States, the Package Recycle Law which prescribes the dutyof recovering and reusing plastics was enacted in 1995. In view of thesecircumstances, various attempts have recently been made to reuseplastics waste as resources. However, two decades after the enactment ofthis law, only 8% of all plastics waste is actually recycled. Clearly,there are environmental drivers toward increasing the rate of recycling.However, logistical and abiding societal factors still dictate that thevast majority of plastics waste is dumped, or even worse, incinerated.

A further consideration is that the mineral cost of supplying the worldwith its ever-increasing demand for plastics accounts for approximately7% of the global crude oil consumption on an annual basis. In brief, itcosts oil to make plastics—and unless that oil is recoverable once theplastics has served its commercial purpose, our global mineral debt onlyserves to increase.

The Japanese inventor Akinori Ito popularised the idea of convertingwaste plastics back into fuel oil through plastic pyrolysis. Pyrolysisis a thermochemical decomposition of organic material, such as plastics,at elevated temperature in the absence of oxygen. It involves thesimultaneous change of chemical composition and physical phase, and isirreversible. Pyrolysis typically occurs at temperatures in the range of400-900° C., at small excess pressure. This process, for example, iswidely used in petroleum refinery for obtaining low molecular monomersfrom naphtha, and it can used for waste plastics processing with fuelsproduction as an alternative of its incineration or landfilling.

In this process, the long polymer molecules of plastics materials arebroken down into shorter chains of hydrocarbons with the help of heatand pressure. Essentially, the process mimics nature in which organicmaterials are broken down into oil over thousands or even millions ofyears. The pyrolysis process achieves this with intense heat in aclosed, anaerobic system over a short period. A catalyst can be used tolower the temperature and increase the yield. Other substances which canbe pyrolysed are biomass, waste tires, lubricating oils, coal andpetroleum residues; waste tire pyrolysis being the most popular and themost profitable of them all.

The basic process of pyrolysis proceeds as follows: (1) A shredding stepin which the waste material must be segregated and, if possible,cleaned. Then it is shredded to speed up the reaction and to ensure thatthe reaction is complete. (2) An anaerobic heating step in which theshredded material is heated in a controlled manner in an oxygen-freereactor. One of the most crucial factors in this operation ismaintaining the correct temperature (˜430° C. for plastics) and the rateof heating, as they define the quality and the quantity of the finalproduct. (3) A condensation step in which the gas that comes out fromthe reactor is condensed by passing it through a condensation tube or bydirectly bubbling it in water. (4) A distillation step in which theresultant mixture of oil can be used as furnace oil but isinsufficiently pure for engines. In order to be able to use it as enginefuel, the desired products need to be extracted and purified from themixture through fractional distillation, or some other purificationmeans.

Some of the benefits of pyrolysis are that the process does not generateharmful pollutants and that the by-products can be used as fuel forrunning the plant. In the case of plastics, some of the valuable fuelsand solvents that can be extracted through waste plastic pyrolysis aregasoline, kerosene, diesel, benzene, LPG, toluene and xylene. Moreover,the pyrolytic process is relatively efficient in that one kilogram ofwaste can yield up to one litre of fuel. By direct comparison,incineration of the same quantity of plastics would produce threekilograms of carbon dioxide.

Anhydrous pyrolysis can be used to produce liquid fuel similar to dieselfrom plastic waste, with a higher cetane value and lower sulfur contentthan traditional diesel. Using pyrolysis to extract fuel fromend-of-life plastics is a second-best option after recycling, isenvironmentally preferable to landfill, and can help reduce dependencyon foreign fossil fuels and geo-extraction. Moreover, plastics-deriveddiesel fuel is obtainable in a form pure enough for commercial sale andconsumption. On the other hand, such technologies are still in theirinfancy—and it is a known goal of the art to find ever more efficientmeans of obtaining fuels from waste plastics.

European patent application 0 620 264 A2 discloses a process for makinga lube oil from waste plastics. The process utilises a cracking processin a fluidised bed of inert solids and fluidised with, for instance,nitrogen. The product of the cracking is hydrotreated over an aluminacatalyst or other refractory metal oxide support containing a metalcomponent, and then optionally catalytically isomerised. The overallyield, however, is lower than desired. The isomerisation catalyststaught partially cause this result. There is no teaching of using betterisomerisation catalysts. Also, EP 0 620 264 A2 does not teach a processof producing a high yield of heavy lube oils.

Many methods for preparing low-boiling hydrocarbons from waste plasticsand high-boiling hydrocarbons are known. U.S. Pat. No. 4,851,601describes a reaction of pyrolysis in a reactor kettle (vertical orhorizontal), wherein the outside wall of the kettle is heated at a hightemperature while the materials therein are heated indirectly. In thismethod, the outside wall is apt to be deformed when the reactor isheated directly at a high temperature. The materials are readilysintered on the inside wall because of local over-heating so that theconversion yield of the reaction and the life of the reactor are greatlydecreased. In addition, the coefficient of the reactor's heat transferis relatively low, it is difficult to drain the reaction residues, andthe catalytic reaction in the fixed bed needs a separate heat supply.These are the common drawbacks of the reactor kettle in the prior art.

A spiral reactor utilised in some special fields is similar to theabove. Heat is indirectly transferred when it works. The outside wall ofthe reactor is heated directly at a high temperature, making thematerials in the reactor indirectly heated. Therefore, the heat transfercoefficient is not satisfactory.

It will be appreciated also that the desirability of working a method ofextracting diesel from plastics may be of limited appeal in cases wherethe method itself gives rise to significant quantities of contaminatedwaste solvents. Accordingly, it would also be advantageous to providemeans for regenerating or recycling spent solvents used in theextraction method.

Thus, in a preferred form, one or more embodiments of the presentlydisclosed concepts are able to operate as an effective standalonecontinuous (or indeed batch, if desired) process, at once providing forthe extraction of diesel from waste plastics and the recycling of thesolvents used to perform the extraction.

Although the general principles disclosed herein are describedhereinafter with reference to specific examples, it will be appreciatedby those skilled in the art that they may be embodied in many otherforms.

Any discussion of documents, acts, materials, devices, articles or thelike which has been included in the present specification is not to betaken as an admission that any or all of these matters form part of theprior art base or were common general knowledge in the field relevant tothe present disclosure as it existed before the priority date of eachclaim of this application.

SUMMARY

Throughout this specification, the word “comprise”, or variations suchas “comprises” or “comprising”, will be understood to imply theinclusion of a stated element, integer or step, or group of elements,integers or steps, but not the exclusion of any other element, integeror step, or group of elements, integers or steps.

In a first aspect, there is provided a kiln for use in the production ofhydrocarbon fuels from plastics, the kiln comprising:

a reaction chamber;

a feed inlet for feeding plastic feed material into the reactionchamber;

a heater for heating the reaction chamber; and

a scrubber in direct fluid communication with the reaction chamber;

wherein the kiln is configured such that plastic feed material in thereaction chamber is heated in an absence of oxygen thereby to decomposeat least a portion of the plastic feed material into a reaction chambergas product stream comprising hydrocarbons suitable for use as fuel, and

wherein the scrubber is configured to remove hydrocarbons in thereaction chamber gas product stream above a predetermined upperhydrocarbon range for returning to the reaction chamber for furtherheating in the absence of oxygen.

The kiln may be configured such that the temperature of the reactionchamber gas product stream exiting the reaction chamber does not dropsubstantially before entering the scrubber.

The scrubber may be configured such that a scrubber gas stream exitingthe scrubber is at a temperature of less than 350° C.

The kiln may be a cylindrical horizontal kiln comprising a cylindricalouter shell and the reaction chamber may comprise an inner tubepositioned concentrically in the cylindrical outer shell.

The heater for heating the reaction chamber may comprise a heat flowmedium flowing in an annulus defined between the central inner tube andouter shell, such that the heat source medium heats an outer surface ofthe inner tube.

The outer surface of the inner tube may comprise a plurality of vortexgenerators for increasing heat transfer efficiency from the heat sourcemedium to the reaction chamber.

The kiln may further comprise a stirrer for stirring the plastic feedmaterial in the reaction chamber. Additionally, the kiln may furthercomprise a catalyst in the reaction chamber for pushing the reactiontowards hydrocarbons of desirable chain length and/or desired aromatichydrocarbons.

The kiln may further comprise a waste particulate outlet for removingwaste particulate material from the reaction chamber.

In a second aspect, there is provided a system for the production ofhydrocarbon fuels from plastics, the system comprising a kiln accordingto the first aspect.

The system may further comprise at least one hydrocarbon recovery devicefor recovering hydrocarbons within a predetermined hydrocarbon range.The at least one hydrocarbon recovery device may be one or more of: afractionation column configured to condense diesel range hydrocarbonsfrom a hydrocarbon gas stream; a condenser configured to condense petrolrange hydrocarbons from a hydrocarbon gas stream; and/or a compressiondevice configured to condense liquid petroleum gas (LPG) rangehydrocarbons from a hydrocarbon gas stream. It will be appreciated thatthe selection of equipment for condensing hydrocarbon gases leaving thekiln will depend on the desired final product.

The fractionation column may be in fluid communication with a gas outletof the scrubber. The fractionation column may be further configured todivert at least a portion of condensed diesel to the scrubber for use asa scrubbing liquid.

A vacuum tower may be provided for removing water from diesel rangehydrocarbons condensed by the fractionation column.

The condenser may be in fluid communication with a gas outlet of thefractionation column.

The compression device may be in fluid communication a gas outlet of thecondenser.

In a third aspect, there is provided an assembly for use in theproduction of hydrocarbon fuels from plastics, the assembly comprising:

a kiln comprising:

-   -   a reaction chamber;    -   a feed inlet for feeding plastics feed material into the        reaction chamber; and    -   a heater for heating the reaction chamber,    -   wherein the kiln is configured such that plastics feed material        in the reaction chamber is heated in an absence of oxygen        thereby to decompose at least a portion of the plastics feed        material into a reaction chamber gas product stream comprising        hydrocarbons suitable for use as fuel,

a scrubber in fluid communication with the reaction chamber, wherein thescrubber is configured to remove hydrocarbons in the reaction chambergas product stream above a predetermined upper hydrocarbon range andreturn the removed hydrocarbons to the reaction chamber for furtherheating in the absence of oxygen; and

a hydrocarbon recovery device in fluid communication with the scrubberfor receiving a remainder of the reaction chamber gas product stream,the hydrocarbon recovery device being configured to remove hydrocarbonswithin a predetermined hydrocarbon range from said remainder.

In a fourth aspect there is provided a method for deriving fuel fromplastics, the method comprising subjecting a quantity of plastics to apyrolytic process, thereby to convert at least a portion of the plasticsto a crude fuel; and extracting the fuel in a directly usable form byway of:

a first extraction step comprising counterflow liquid-liquid extractionusing one or more extraction solvents to extract one or more impuritiesfrom the crude fuel;

a second extraction step comprising counterflow extraction of theresultant contaminated one or more extraction solvents from the firstextraction step; and

optionally, an extraction solvent purification step wherein thecontaminated one or more extraction solvents are purified to enabletheir re-use in a subsequent one or more of the extraction steps.

In an embodiment, the second extraction step comprises using a highlypolar liquid such as water, alcohol, or the like, or mixtures thereof toincrease the polarity of the contaminated extraction solvent, in turncausing the extraction solvent to reject the extract; and thendistilling the one or more polar compounds from the extraction solvent.

The method defined according to the fourth aspect may be substantiallyas depicted with respect to FIGS. 2 and 3 of the accompanying drawings.

In a fifth aspect there is provided a method for deriving fuel fromplastics, the method comprising subjecting a quantity of plastics to apyrolytic process, thereby to convert at least a portion of the plasticsto a crude fuel; and extracting the fuel in a directly usable form byway of:

a first extraction step comprising counterflow liquid-liquid extractionusing one or more extraction solvents to extract one or more impuritiesfrom the crude fuel;

a second extraction step comprising counterflow extraction of theresultant contaminated one or more extraction solvents from the firstextraction step.

In an embodiment, the second extraction step comprises using a light endnon-polar solvent such as heptanes, hexanes, or the like, or mixturesthereof, that extract aromatics and compounds of similar polarity fromthe extraction solvent; and then distilling the light end solvent fromthe extraction solvent.

The method defined according to the fifth aspect may be substantially asdepicted with respect to FIGS. 4 and 5 of the accompanying drawings.

In one or more embodiment, the extraction solvent isN-methyl-2-pyrrolidone, or similar dipolar aprotic solvents such asdimethylformamide, dimethyl sulfoxide or the like. However, it will beappreciated that any solvent having appropriate physical and polarcharacteristics may be used.

In one or more embodiment, the extraction solvent purification step isperformed. Performing the extraction solvent purification step in asubstantially continuous manner provides for substantially continuousoperation of the first and/or second extraction steps.

In one or more embodiment, in the counterflow extraction, the extractionsolvent enters the top of a packed column and the crude fuel enters thebottom of the packed column. Alternatively, the extraction solvententers the bottom of a packed column and the crude fuel enters the topof the packed column.

In one or more embodiment, the extraction solvent extracts impuritiesresulting in contaminated extraction solvent exiting the bottom of thepacked column and purified fuel exiting the top of the packed column.Alternatively, the contaminated extraction solvent may exit the top of apacked column and the purified fuel may exit the bottom of the packedcolumn.

In one or more embodiment, the contaminated extraction solvent is mixedwith water, alcohol, or the like, or mixtures thereof which causes thenon-polar compounds such as aromatics to come out of solution. Suitablesolvents would be anything having a polarity in the range of alcohols towater.

In one or more embodiment, the impurity compounds flow off theextraction solvent which is contaminated with the water.

In one or more embodiment, the water is distilled out of the extractionsolvent using conventional rising film evaporators. This distillationmay or may not occur under vacuum and may or may not employ a series ofmulti-effect evaporators to reduce distillation thermal energyrequirements. Distillation may be effected by conventional techniques.

In one or more embodiment, both the water and the extraction solvent arerecycled. This recycling has clear environmental and economicadvantages, as well as liberating some residual crude pyrolysis productwhich can be disposed of, but is otherwise employed as a marine dieselfuel or boiler fuel.

In one or more embodiment, in the counterflow extraction, the extractionsolvent enters the top of a packed column and the crude fuel enters thebottom of the packed column. Alternatively, in the counterflowextraction, the extraction solvent may enter the bottom of a packedcolumn and the crude fuel may enter the top of the packed column.

In one or more embodiment, the extraction solvent extracts impuritiesresulting in contaminated extraction solvent exiting the bottom of thepacked column and purified fuel exiting the top of the packed column.Alternatively, the contaminated extraction solvent may exit the top ofthe packed column and purified fuel may exit the bottom of the packedcolumn.

In one or more embodiment, the contaminated extraction solvent is pumpedto another counterflow extraction set-up which uses the light endnon-polar solvent to extract aromatics, sulfur compounds and similarfrom the extraction solvent.

In one or more embodiment, the light end non-polar solvent is distilledand recycled leaving concentrated aromatics, sulfur compounds andsimilar and clean extraction solvent.

In one or more embodiment, both the light end non-polar solvent and theextraction solvent are recycled.

In one or more embodiment, the fuel is a diesel blend.

In one or more embodiment, the plastics are waste plastics otherwisedestined for recycling, landfill, or incineration.

In one or more embodiment, the pyrolytic process by which the plasticsare converted to the crude fuel takes place at about 450° C., over aperiod of about 30 minutes. However, it will be appreciated that anytemperature and period over which pyrolysis can be effected isapplicable to the present invention.

In one or more embodiment, the first and second extractions steps takeplace at substantially ambient pressure, at about 80° C. and over acounterflow extraction period of less than about 20 minutes. However, itwill be appreciated that any pressure, temperature and period over whichextraction can be effected is applicable to the presently disclosedprinciples.

In one or more embodiment, the method is adapted to be scalable to acommercial scale of greater than 1000 tons fuel per day. In one or moreembodiment, the method is also scalable to a pilot plant scale.

In one or more embodiment, the method gives rise to yields of about 70%w/w diesel and about 15% w/w gasoline per unit plastics. However, to anappreciable extent, the recovery of fuel from the waste plastics isdictated firstly by the composition of the waste plastics and by theconditions (temperature, pressure, period) under which the pyrolysisstep is effected.

In one or more embodiment, the extraction solvent isN-methyl-2-pyrrolidone (NMP; CAS 872-50-4).

In one or more embodiment, the fuel is directly transferable tocommercial at-the-pump sale and meets the Australian Diesel Fuel QualityStandard (Fuel Standard (Automotive Diesel) Determination 2001, asamended, made under section 21 of the Fuel Quality Standards Act 2000).

In one or more embodiment, the method is adaptable to be financiallyprofitable down to about AU$16/bbl oil. However, it will be appreciatedthat as the method is refined and made more efficient, the profitabilityon a per-barrel basis will increase accordingly.

In one or more embodiment, the waste product obtained followingrecycling of the extraction solvent is adaptable for use as a boilerfuel or marine diesel oil, or can be stored.

In one or more embodiment, the extraction solvent purification stepcomprises the contaminated one or more extraction solvents entering arising film evaporator at between about −80 and −90 kPa.

The method of the fourth and/or fifth aspects may be performed on crudefuel output from the kiln, system or assembly of the first, second orthird aspects.

In a sixth aspect there is provided a diesel blend fuel when obtained bya method as defined according to the fourth or fifth aspects. In one ormore embodiment, the fuel is directly transferable to commercialat-the-pump sale and meets the Australian Diesel Fuel Quality Standard(Fuel Standard (Automotive Diesel) Determination 2001, as amended, madeunder section 21 of the Fuel Quality Standards Act 2000), as well asASTM D975-15c and EN590 standards.

In a seventh aspect there is provided recycled one or more extractionsolvents when obtained by a method as defined according to the fourth orfifth aspects.

In one or more embodiment, the recycled one or more extraction solventsare found to be of sufficient purity to allow their re-use in a furtherone or more iterations of the process disclosed herein.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the presently disclosed kiln will now be described by wayof example only, with reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of a system for the conversion of plasticsto hydrocarbon fuels;

FIG. 2 is a schematic diagram of an embodiment of a method for derivingfuel from plastics;

FIG. 3 represents the same process as that depicted in FIG. 2, with anadditional NMP solvent purification step being signified;

FIG. 4 is a schematic diagram of a further embodiment of a method forderiving fuel from plastics;

FIG. 5 represents the same process as that depicted in FIG. 4, with anadditional NMP solvent purification step being signified;

FIG. 6 is a schematic representation of a back-end NMP solventpurification process as defined in certain embodiments of the presentlydisclosed principles;

FIG. 7 is a photograph of a crude plastic-derived diesel followingpyrolysis of crude waste plastics;

FIG. 8 is a photograph of an extraction step; and

FIG. 9 is a final purified diesel product following the NMP extractionsteps.

DESCRIPTION OF EMBODIMENTS

Referring to FIG. 1, there is provided a system 10 for the conversion ofplastics to hydrocarbon fuels such as diesel, petrol and liquidpetroleum gas (LPG). The classification of hydrocarbon fuels dependsprimarily on the range of chain lengths of the hydrocarbons in the fuelmix, for example diesel hydrocarbons typically range from C10 to C25,petrol hydrocarbons from C4 to C12, and liquid petroleum gas (LPG)typically comprises a mixture of propane (C₃H₈) and butane (C₄H₁₀).

The system 10 comprises a plastic feed material 500 being fed to a kiln100. The plastic feed material 500 may be any plastic material formed oflong-chain organic polymers, for example waste plastic materials such asplastic packaging or automotive tyres. The plastic feed material 500 mayundergo pre-processing prior to introduction into the kiln 100, forexample shredding or chopping to improve handling and surface area ofthe plastic feed material, or drying to minimise the amount of waterintroduced to the system. The plastic feed material 500 is fed to a feedinlet 110 of the kiln 100 by a feeder 120 in a manner so as to reduceheat and gas loss from the kiln. For example, the plastic feed material500 may be fed to the feed inlet 110 using a double slide-gate feeder ora plug screw feeder. The feeder 120 also allows for the control of therate of flow of the plastic feed material 500 into the kiln 100.

The kiln 100 is a cylindrical horizontal kiln comprising a reactionchamber 130 in the form of a central inner tube through which theplastic feed material 500 flows, and a heater comprising a heat source800 for heating the reaction chamber. The reaction chamber 130 comprisesa plurality of stirrers 140 mounted at right angles to a horizontalrotating shaft 150 for stirring the plastic feed material in thereaction chamber 130. In addition to improving heat transfer to theplastic feed material 500, the rotating stirrers 140 also assist in theremoval of waste particulate material from the reaction chamber 130 andprevention of waxy build-up on the reaction chamber 130 inner walls.

The heat source 800 may be any suitable heat source for heating thereaction chamber 130 and its contents, such as a heat source mediumwhich flows through an annular region between a concentric outer tube160 and the reaction chamber 130, the heat source medium 800transferring heat through an outer wall of the reaction chamber 130. Theheat source medium 800 may be sourced from other process equipment usedin or in conjunction with the system, for example the heat source medium800 may be combustion gases from a cyclone combustor 170 used to treatwaste products from the system, such as non-condensable gases and char.The outer wall of the reaction chamber 130 further comprises a pluralityof vortex generators (not shown) to increase heat transfer efficiencybetween the heat source medium 800 and the reaction chamber 130.

In the reaction chamber 130, the plastic feed material 500 is heated inthe absence of oxygen such that at least a portion of the plastic feedmaterial 500 first melts, then decomposes into a reaction chamber gasproduct stream 501 comprising hydrocarbons ranging from hydrogen toheavy wax, with the majority of the gases being in the liquid fuelrange. A catalyst such as activated bauxite may further be provided inthe reaction chamber 130 for pushing the reaction towards hydrocarbonsof desirable chain length and/or desired aromatic hydrocarbons. Wasteparticulate material such as char, dust and ash may also be formed inthe reaction chamber 130 as the plastic feed material 500 is heated ormay be introduced with the plastic feed material 500. The kiln isprovided with a waste particulate outlet 180 in fluid communication withthe reaction chamber 130 for removing at least a portion of the wasteparticulate material formed in the reaction chamber.

The kiln 100 further comprises a product outlet 190 and a scrubber 200at the product outlet 190. The reaction chamber gas product stream 501exits the reaction chamber 130 through the product outlet 190 and flowsthrough the scrubber 200. It will be appreciated that the exitingreaction chamber gas product stream 501 may also contain a portion ofthe above described waste particulate material. The scrubber 200 ispreferably a packed scrubbing column comprising plate or ring-typepacking. In the scrubber 200, the reaction chamber gas product stream501 is brought into contact with a hydrocarbon scrubbing liquid 502 forcondensing heavier, higher boiling point, hydrocarbons present in thereaction chamber gas product stream 501, wherein the condensedhydrocarbons and the scrubbing liquid flow back into the reactionchamber to undergo further reaction. The remaining, lighter weight,hydrocarbons exit the scrubber as a scrubber gas product stream 503. Thescrubbing liquid 502 also acts to wash the reaction chamber gas productstream 501 of waste particulate material which flows back to thereaction chamber 130 with the scrubbing liquid 502 and the condensedheavier hydrocarbons.

It will be appreciated that the scrubber 200 is in direct fluidcommunication with the reaction chamber 130 such that the reactionchamber gas product stream 501 exiting the reaction chamber 130 flowsdirectly to the scrubber 200. This minimises any cooling of the reactionchamber gas product stream 501 prior to entering the scrubber 200 whichmay lead to the formation of solid waxy residue being deposited inconduits connecting the reaction chamber 130 and the scrubber 200. Theabove described relative positioning of the reaction chamber 130 and thescrubber 200 further avoids the need to reheat the product from thereaction chamber 130 in order to separate out the desired hydrocarbons.

The system 10 further comprises at least one hydrocarbon recovery devicefor recovering hydrocarbons within a predetermined hydrocarbon range. Inthe system 10 of FIG. 1, there is provided a number of hydrocarbonrecovery devices, discussed in more detail below, for recovering variouscomponents of the hydrocarbon gas product stream produced in the kiln,including a fractionation column 210 configured to condense diesel rangehydrocarbons, a condenser 240 configured to condense petrol rangehydrocarbons, and a gas compression and cooling device configured tocondense liquid petroleum gas (LPG) range hydrocarbons.

The scrubber gas product stream 503 then enters a fractionation column210 where the scrubber gas product stream 503 is brought into contactwith a hydrocarbon reflux 504 selected for causing diesel rangehydrocarbons 506 to condense and flow to out bottom of the fractionationcolumn 210 while the gasoline and lighter hydrocarbons exit the top ofthe fractionation column 210 as a fractionation gas product stream 505.A portion of the diesel range hydrocarbons 506 exiting the fractionationcolumn 210 is used as the scrubbing liquid 502 for scrubbing thereaction chamber gas product stream 501.

The remaining diesel 507 may then be treated prior to storage is adiesel storage vessel. In one example, the remaining diesel 507 istreated to remove moisture, for example by vacuum drying 220, and withthe treated diesel 508 collected and stored in a diesel storage vessel230. In another example, the diesel may undergo a solvent extractionprocesses, as discussed in more detail below, to extract impurities suchas aromatics, sulphur compounds and similar.

It will be appreciated that the operation conditions of the kiln 100 andscrubber 200 will be dependent on the type of plastic feed material 500to be processed and the desired hydrocarbon product to be recovered. Forexample, the targeted recovery of the lighter weight liquid petroleumgas (LPG) range hydrocarbons may require higher operating temperaturesin the kiln than for the targeted recovery of diesel range hydrocarbons.While temperature in the kiln 100 is important, careful control of thetemperature at the product outlet 190 (i.e. the scrubber inlet) and thescrubber outlet can play an important role in the composition of thefinal products. These temperatures can be controlled, for example, bycontrolling the temperature in the reaction chamber 130 and/orcontrolling the flow rate of the scrubbing liquid 502 into the scrubber200. Preferably, the temperature of the scrubber gas stream 503 exitingthe scrubber is maintained below 350° C. such that heavy, long-chainhydrocarbons unsuitable for use as fuel, condense and flow back to thereaction chamber 130 for further treatment.

The fractionation gas product stream 505 exiting the fractionationcolumn 210 flows through a condenser 240 configured to condense thepetrol range hydrocarbons 504, 509 in the fractionation gas productstream 505. A portion of the condensed petrol range hydrocarbons exitingthe condenser are used as the hydrocarbon reflux 504 for thefractionation column 210. The remaining petrol 509 is collected andstored in a petrol storage vessel 250. As described above for the diesel507, the petrol 509 may be treated prior to storage in petrol storagevessel. For example, the petrol 509 may undergo a solvent extractionprocesses, as discussed in more detail below, to extract impurities suchas aromatics, sulphur compounds and similar.

Any remaining gases that were not condensed in the condenser 240, i.e.due to very low molecular weight and low boiling points, exit thecondenser 240 as a condenser gas product stream 510. The condenser gasproduct stream 510 is fed to a gas compression and cooling device 260configured to extract liquid petroleum gas (LPG) range hydrocarbons fromthe condenser gas product stream 510. The extracted LPG rangehydrocarbons 511 are collected and stored in a LPG storage vessel 270.

Non-condensable gases 512 that are not recovered in the gas compressionand cooling device 260 may be used in other process equipment, such asto at least partially fuel the cyclone combustor 170 as described above.

Referring now to FIG. 2 of the accompanying drawings, there is provideda schematic diagram of the process represented according to the fourthaspect. This aspect defines a method for deriving fuel from plastics,the method comprising a preliminary step subjecting a quantity ofplastics to a pyrolytic process (not shown), thereby to convert at leasta portion of the plastics to a crude fuel, in this case, crude diesel(1). The pyrolytic process by which the plastics are converted to thecrude fuel takes place at about 450° C., over a period of about 30minutes.

It will be appreciated that the pyrolytic process may be that describedwith reference to the kiln 100 above, with the crude fuel being any ofthe described hydrocarbon fuel streams, e.g. diesel 507, petrol 509,resulting from the operation of the kiln 100.

The process comprises a first extraction step obtaining the fuel in adirectly usable form by way of: a first extraction step comprisingcounterflow liquid-liquid extraction in a packed column (2) using one ormore extraction solvents (3), preferably in the form ofN-methyl-2-pyrrolidone (NMP). The NMP serves to extract one or moreimpurities from the crude fuel. The purified diesel (4) is obtained froman exit stream, either at the top, or bottom of the packed column (2).

The process then comprises a second extraction step comprisingcounterflow extraction of the resultant contaminated NMP from the firstextraction step (5). The second extraction step comprises using water,alcohol, or the like, or mixtures thereof (6A) to increase the polarityof the contaminated extraction solvent, in turn causing the extractionsolvent to reject the extract. The second counterflow step again takesplace in a packed column (7) and gives rise to an exit stream ofcontaminants (8A) such as sulfur compounds, aromatics, etc., and an exitstream of water-contaminated NMP solvent (9).

Optionally, an extraction solvent purification step is performed,wherein the contaminated extraction solvents are purified to enabletheir re-use in a subsequent one or more of the extraction steps; thiswill be discussed further, below.

The first and second extractions steps take place at substantiallyambient pressure, at about 80° C. and over a counterflow extractionperiod of less than about 20 minutes.

In a final step, the water-contaminated NMP solvent (9) is thendistilled using a standard distillation column (10), which gives rise torecycled water (11A) and recycled NMP (12). The waste product obtainedfollowing recycling of the extraction solvent is adaptable for use as aboiler fuel or marine diesel oil.

It will be appreciated that the extraction of the purified diesel (4)takes place within the first extraction step, with the second extractionstep and subsequent distillation steps serving to provide a means ofrecycling the NMP and water solvents.

The method is adapted to be scalable to a commercial scale of greaterthan 1000 tons fuel per day. However, during scale-up, the method isalso scalable to a pilot plant scale.

The method gives rise to yields of about 70% w/w diesel and about 15%w/w gasoline per unit plastics. However, to an appreciable extent, therecovery of fuel from the waste plastics is dictated firstly by thecomposition of the waste plastics and by the conditions (temperature,pressure, period) under which the pyrolysis step is effected.

The purified diesel fuel is directly transferable to commercialat-the-pump sale and meets the Australian Diesel Fuel Quality Standard(Fuel Standard (Automotive Diesel) Determination 2001, as amended, madeunder section 21 of the Fuel Quality Standards Act 2000).

It will be appreciated that the process as depicted according to FIG. 3is substantially the same as that of FIG. 2, with the additionalextraction solvent purification step being performed.

Often, it is found that there is a heavy contaminant in the extractionsolvent/s (NMP) that is not removed other than by one or more deliberatepurification steps. It is found that the contaminant may be one or moreheavy hydrocarbons with a boiling point higher than NMP. Thus the NMPcan be purified by an additional simple distillation step as depicted inFIG. 6 and discussed below.

For completeness, and with regard to FIG. 4 of the accompanyingdrawings, there is provided a schematic diagram of the processrepresented according to the fifth aspect. In the ensuing description ofthe second aspect, actions or reagents equivalent with those referencedin the fourth aspect (FIGS. 2 and 3) have been given consistentdesignations, e.g., NMP (3), etc.

The fifth aspect defines a method for deriving fuel from plastics, themethod comprising a preliminary step subjecting a quantity of plasticsto a pyrolytic process (not shown), thereby to convert at least aportion of the plastics to a crude fuel, in this case, crude diesel (1).The pyrolytic process by which the plastics are converted to the crudefuel takes place at about 450° C., over a period of about 30 minutes.

The process comprises a first extraction step obtaining the fuel in adirectly usable form by way of: a first extraction step comprisingcounterflow liquid-liquid extraction in a packed column (2) using one ormore extraction solvents (3), preferably in the form ofN-methyl-2-pyrrolidone (NMP). The NMP serves to extract one or moreimpurities from the crude fuel. The purified diesel (4) is obtained froman exit stream, either at the top, or bottom of the packed column (2).

The process then comprises a second extraction step comprisingcounterflow extraction of the resultant contaminated NMP from the firstextraction step (5). The second extraction step comprises using hexanes,heptanes, or the like, or mixtures thereof (6B) to change the polarityof the contaminated extraction solvent, in turn causing the extractionsolvent to reject the extract. The second counterflow step again takesplace in a packed column (7) and gives rise to an exit stream ofcontaminants (8B) such as hexanes and heptanes impurities, etc.

The first and second extractions steps take place at substantiallyambient pressure, at about 80° C. and over a counterflow extractionperiod of less than about 20 minutes.

In a final step, the contaminated NMP solvent (9) is then distilledusing a standard distillation column (10), which gives rise to recycledhexanes/heptanes (11B) and recycled NMP (12). The waste product obtainedfollowing recycling of the extraction solvent is adaptable for use as aboiler fuel or marine diesel oil.

It will be appreciated that the process as depicted according to FIG. 5is substantially the same as that of FIG. 4, with the additionalextraction solvent purification step being performed.

Often, it is found that there is a heavy contaminant in the extractionsolvent/s (NMP) that is not removed other than by one or more deliberatepurification steps. It is found that the contaminant may be one or moreheavy hydrocarbons with a boiling point higher than NMP. Thus the NMPcan be purified by an additional simple distillation step as depicted inFIG. 5 and discussed below.

Referring now to FIG. 6, a separate (or in-line) means is provided forpurifying the contaminated extraction solvents to purity levels thatenable their re-use in subsequent iterations of the process.

In the purification step/s depicted in FIG. 6, contaminated NMP (12)with remaining contaminant enters a rising film evaporator (D) that isheated generally by steam or heat transfer oil (13). The rising filmevaporator is under vacuum on the NMP side. Generally the vacuumconditions will be between about −80 and −90 kPa. Generally thetemperature of the rising film evaporator will be controlled tofacilitate the boiling of the NMP at the desired vacuum The NMP boilsoff as NMP vapour (14) leaving the heavy contaminant and in condensed inthe NMP vacuum condenser (E). The heavy contaminants (17) leave therising film evaporator for use as industrial heating fuel or furtherrefining. The recycled and purified NMP (16) is then returned tosubsequent iterations of the extraction method.

In respect of each of the aspects described above, it will beappreciated that the extraction of the purified diesel (4) takes placewithin the first extraction step, with the second extraction step andsubsequent distillation steps serving to provide a means of recyclingthe NMP and water solvents.

The method is adapted to be scalable to a commercial scale of greaterthan 1000 tons fuel per day. However, during scale-up, the method isalso scalable to a pilot plant scale.

The method gives rise to yields of about 70% w/w diesel and about 15%w/w gasoline per unit plastics. However, to an appreciable extent, therecovery of fuel from the waste plastics is dictated firstly by thecomposition of the waste plastics and by the conditions (temperature,pressure, period) under which the pyrolysis step is effected. Thepurified diesel fuel is directly transferable to commercial at-the-pumpsale and meets the Australian Diesel Fuel Quality Standard (FuelStandard (Automotive Diesel) Determination 2001, as amended, made undersection 21 of the Fuel Quality Standards Act 2000).

FIG. 7 depicts a sample of crude plastic-derived diesel followingpyrolysis of the crude waste plastics. Notable features are its darknessand its opacity. This crude product is unsuitable for commercial saleat-the-pump. FIG. 8 is a photograph of an extraction step in which NMPis mixed with the sample and allowed to settle out to the bottom. Theimpurities/contaminants dissolve out into the NMP; the relatively clearlayer remaining on top is relatively pure diesel. FIG. 9 depicts asample of the final purified diesel product following the NMP extractionsteps. As noted elsewhere, the fuel is directly transferable tocommercial at-the-pump sale and meets the Australian Diesel Fuel QualityStandard (Fuel Standard (Automotive Diesel) Determination 2001, asamended, made under section 21 of the Fuel Quality Standards Act 2000),as well as ASTM D975-15c and EN590 standards.

It will be appreciated that the above-described methods enable theconversion of waste plastics into a commercially useful form by way ofpurified diesel fuel. Moreover, the inventive method provides means forrecycling any solvents used in such an extraction process.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the above-describedembodiments, without departing from the broad general scope of thepresent disclosure. The present embodiments are, therefore, to beconsidered in all respects as illustrative and not restrictive.

1.-44. (canceled)
 45. A method for deriving fuel from plastics, themethod comprising subjecting a quantity of plastics to a pyrolyticprocess, thereby to convert at least a portion of the plastics to acrude fuel; and extracting the fuel in a directly usable form by way of:a first extraction step comprising counterflow liquid-liquid extractionusing one or more extraction solvents to extract one or more impuritiesfrom the crude fuel; and a second extraction step comprising counterflowextraction of resultant contaminated extraction solvent(s) from thefirst extraction step.
 46. The method according to claim 45, wherein thesecond extraction step comprises changing the polarity of the resultantcontaminated extraction solvent(s), thereby causing the resultantcontaminated extraction solvent(s) to reject the extracted one or moreimpurities; and removing the rejected one or more impurities, therebyresulting in decontaminated extraction solvent(s).
 47. The methodaccording to claim 46, comprising reversing the polarity of thedecontaminated extraction solvent(s).
 48. The method according to claim46, wherein the polarity of the resultant contaminated extractionsolvent(s) is changed by addition of one or more polar compoundsthereto; and wherein the polarity of the decontaminated extractionsolvent(s) is reversed by distilling the one or more polar compoundstherefrom to produce purified extraction solvent(s) for reuse in thefirst extraction step.
 49. The method according to claim 48, comprisingcollecting the one or more polar compounds distilled from thecontaminated extraction solvent(s) for reuse in the method.
 50. Themethod according to claim 45, wherein the second extraction stepcomprises adding a light end non-polar solvent, or a mixture of lightend non-polar solvents, to the extraction solvent(s) obtained from thefirst extraction step to extract therefrom aromatics and compounds ofsimilar polarity to that of the light end non-polar solvent(s); and thenremoving the light end non-polar solvent(s) by distillation.
 51. Themethod according to claim 45, wherein the extraction solvent(s)comprise(s) one or more solvents selected from the group consisting of:N-methyl-2-pyrrolidone; and dipolar aprotic solvents.
 52. The methodaccording to claim 45, comprising purifying the resultant contaminatedextraction solvent(s) for reuse in the first extraction step.
 53. Themethod of claim 52, wherein purification of the resultant contaminatedextraction solvent(s) is performed in a substantially continuous mannerto provide for substantially continuous operation of the first andsecond extraction steps.
 54. The method according to claim 52, whereinpurification of the resultant contaminated extraction solvent(s)comprises the resultant contaminated extraction solvent(s) entering arising film evaporator under vacuum.
 55. The method according to claim45, wherein, in the counterflow extraction of the first extraction step,the extraction solvent(s) enter(s) the top of a packed column and thecrude fuel enters the bottom of the packed column.
 56. The methodaccording to claim 55, wherein the resultant contaminated extractionsolvent(s) carrying the impurities exit(s) the bottom of the packedcolumn, and purified fuel exits the top of the packed column.
 57. Themethod according to claim 45, wherein the fuel is a diesel blend. 58.The method according to claim 45, wherein the pyrolytic process by whichthe plastics are converted to the crude fuel takes place at from about300° C. to about 450° C., over a period of about 30 minutes.
 59. Themethod according to claim 45, wherein the first and second extractionsteps take place at substantially ambient pressure, at about 80° C. andover a counterflow extraction period of less than about 20 minutes. 60.The method according to claim 45, wherein the crude fuel is ahydrocarbon fuel obtained from plastics processed using a kilncomprising: a reaction chamber; a feed inlet for feeding plastics feedmaterial into the reaction chamber; a heater for heating the reactionchamber; and a scrubber in direct fluid communication with the reactionchamber; wherein the kiln is configured such that plastics feed materialin the reaction chamber is heated in an absence of oxygen thereby todecompose at least a portion of the plastics feed material into areaction chamber gas product stream comprising hydrocarbons suitable foruse as fuel, and wherein the scrubber is configured to removehydrocarbons in the reaction chamber gas product stream above apredetermined upper hydrocarbon range for returning to the reactionchamber for further heating in the absence of oxygen.